A program has been initiated to determine the effects of various dietary constituents on the incidence of stroke in the stroke prone strain of rats. Results of preliminary feeding trials indicate that the mortality rate was higher in rats fed a diet manufactured in accordance with a formulation developed in Japan than those fed a purified diet or a standard reference natural ingredient diet. However, the primary course of death was not stroke. These studies have been expanded to include diets that have an excess or are void of specific ingredients so the factors effecting the mortality rates can be isolated. In addition, the blood pressures of a random sample of the animals involved is being evaluated.